In this study, an idea of using multiple layers of adsorbents in adsorption column is proposed for treatment of synthetic wastewater for removal of Cr(VI) ions. In the present study, an effort has been made to study and compare the performance of fixed bed column with single bed adsorbent (RH only) and multi bed adsorbent of Rice Husk (RH), Saw Dust (SD) and Coir Dust (CD) in removal of Cr(VI) from synthetic wastewater and arrive at the parameters of the adsorption column that are useful for process design. From the characterization studies, it has been observed that carbon, aluminium and silica were the major components of the three natural adsorbents studied. It was found that, for better heavy metal removal, natural adsorbents with a percentage of fineness of around 54% could be used in adsorption studies. From the breakthrough curves of single bed and multi bed adsorption columns, it was evident that the multi bed adsorption column performed better. The time taken to achieve the breakthrough point and the exhaustion point in multi bed column is 2.5 times and 1.9 times greater than the time taken by single bed adsorption studies respectively. It was observed that in multi bed adsorption column, at greater bed depths, the significant increase in metal uptake capacity was due to the increase in contact time. Kinetic models viz. Thomas model, Yoon-Nelson model and Bed Depth Service Time model (BDST) were used to predict the performance of the column and sum of squares (SS) error analysis was carried out to test the accuracy of model equations. Higher R2 value and smaller SS value obtained from Thomas model proves that it is suitable to explain the adsorption of Cr(VI) in single and multi bed adsorption column of natural adsorbents. Experimental data fitted well with BDST model where R2 = 0.997. From the cost analysis, multi bed adsorption column was proven to be economical and confirmed that the locally and abundantly available agricultural wastes viz. RH, SD and CD could be used as an alternate to commercially available activated carbon for the removal of Cr(VI) from synthetic wastewater.

中文翻译：

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通过各种动力学模型对多价吸附剂去除六价铬的性能进行评估

在这项研究中，提出了在吸附柱中使用多层吸附剂来处理合成废水以去除 Cr(VI) 离子的想法。在本研究中，已努力研究和比较使用单床吸附剂（仅 RH）和多床吸附剂稻壳 (RH)、锯末 (SD) 和椰壳粉 (CD) 的固定床柱的性能从合成废水中去除 Cr(VI) 并得出对工艺设计有用的吸附塔参数。从表征研究中可以看出，碳、铝和二氧化硅是所研究的三种天然吸附剂的主要成分。研究发现，为了更好地去除重金属，可以在吸附研究中使用细度百分比约为 54% 的天然吸附剂。从单床和多床吸附塔的穿透曲线可以看出，多床吸附塔性能更好。多床塔达到突破点和耗尽点所需的时间分别是单床吸附研究的2.5倍和1.9倍。据观察，在多床吸附柱中，在更大的床深度处，金属吸收能力的显着增加是由于接触时间的增加。动力学模型即。采用Thomas模型、Yoon-Nelson模型和床深服务时间模型（BDST）对柱的性能进行预测，并进行平方和（SS）误差分析以检验模型方程的准确性。Thomas模型得到的较高的R2值和较小的SS值证明适用于解释天然吸附剂单床和多床吸附柱对Cr(VI)的吸附。实验数据与 BDST 模型非常吻合，其中 R2 = 0.997。从成本分析来看，多床吸附柱被证明是经济的，并证实了当地和大量可用的农业废物即。RH、SD 和 CD 可用作市售活性炭的替代品，用于从合成废水中去除 Cr(VI)。多床吸附柱被证明是经济的，并证实了当地和大量可用的农业废物即。RH、SD 和 CD 可用作市售活性炭的替代品，用于从合成废水中去除 Cr(VI)。多床吸附柱被证明是经济的，并证实了当地和大量可用的农业废物即。RH、SD 和 CD 可用作市售活性炭的替代品，用于从合成废水中去除 Cr(VI)。